The present invention generally relates to an apparatus for protecting a satellite reception system from strong terrestrial signals. A high Q tunable trap is used to help reject strong ATSC signals or other signals that may be present on the input coaxial cable of a satellite receiver that operates in a single-wire multi-switch (SWM) environment.
This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Satellite television signals are generally received at a dish antenna, processed by a low-noise block down-converter (LNB), and delivered through the home on coaxial cable to a set-top box (STB) associated with a television display device. In more modern installations, signals from multiple satellite LNBs may be simultaneously transported to multiple STBs on the same coaxial cable by a single-wire multi-switch (SWM).
In some SWM environments, satellite L-band signals (950-2150 MHz) coexist on the same coaxial cable as terrestrial ATSC or other signals from 50-806 MHz. The ATSC signals can be strong enough to overload or damage the satellite front end and need to be attenuated to safe levels. The power from ATSC signals may also cause unwanted attenuation of the desired satellite signal by a wideband RF automatic gain control (AGC) scheme.
With the upper frequency limit of the ATSC spectrum so close to the lower frequency limit of the satellite spectrum, it is difficult to design a satellite high-pass filter of reasonable complexity that can attenuate the ATSC signals without also impacting the lowest satellite frequencies. In many installations, an external diplexer is used to prevent ATSC signals from entering the satellite input connection. However, it would be advantageous if the satellite receiver could continue to operate even if the external diplexer was omitted from the installation. The invention described herein addresses this and/or other problems.